CN110173361B

CN110173361B - Method for operating an internal combustion engine

Info

Publication number: CN110173361B
Application number: CN201910121993.0A
Authority: CN
Inventors: S.海因肯
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2018-02-19
Filing date: 2019-02-19
Publication date: 2023-02-03
Anticipated expiration: 2039-02-19
Also published as: CN110173361A; US20190257241A1; DE102018202477A1; EP3527810A1

Abstract

The invention relates to a method for operating an internal combustion engine (1) having an exhaust gas line (2) which conducts exhaust gas (3) from the internal combustion engine (1) via an exhaust gas turbocharger (4), wherein a second pressure (7) in a second section (8) of the exhaust gas line (2) downstream of the exhaust gas turbocharger (4) is determined by measuring a first pressure (5) in a first section (6) of the exhaust gas line (2) downstream of the internal combustion engine (1) and upstream of the exhaust gas turbocharger (4); the determination of the second pressure (7) is derived from the condition that the first pressure (5) corresponds to the second pressure (7) in the case of a determined crankshaft angle position (10) in a determined operating point (9) of the internal combustion engine (1).

Description

Method for operating an internal combustion engine

Technical Field

The invention relates to a method for operating an internal combustion engine having an exhaust gas line which conducts exhaust gas from the internal combustion engine to the surroundings via an exhaust gas turbocharger. In particular, the method can be used in a motor vehicle for regulating the operation of an internal combustion engine. In addition, by means of the method, the exhaust gas backpressure in the exhaust gas line can be determined and the loading of the exhaust gas treatment component (e.g. a particle filter) with carbon black (Ru β, sometimes referred to as soot) can be determined via a change in the exhaust gas backpressure.

Background

In the case of an internal combustion engine with an exhaust-gas turbocharger, the first section of the exhaust-gas line is downstream of the internal combustion engine and upstream of the exhaust-gas turbocharger and the second section of the exhaust-gas line is downstream of the exhaust-gas turbocharger. In the case of an internal combustion engine, the pressure sensor may be arranged in the first section, for example in an exhaust manifold of the internal combustion engine.

In addition, the internal combustion engine is regulated during operation. In particular, the following adjustments are carried out: adjusting a boost pressure for the internal combustion engine; adjusting the breathing pattern of the internal combustion engine (i.e. the supply of fresh air, exhaust gases, fuel for the combustion in the combustion chamber of the internal combustion engine and the discharge of exhaust gases from the combustion chamber; in addition the ignition moment, the valve opening moment, etc.); diagnosing exhaust turbocharger overspeed; the regeneration of the exhaust gas treatment component arranged in the second section is regulated. These adjustments depend in particular on the exhaust gas back pressure prevailing in the second section of the exhaust line downstream of the exhaust gas turbocharger.

However, the arrangement of the pressure sensor in this only poorly accessible part of the exhaust gas line is costly and costly. Therefore, a way of estimating the exhaust gas back pressure in the second section is known from the prior art.

A method is known from EP 1 491 747 A2, by means of which an exhaust gas back pressure can be determined in a calculable manner.

These estimation or calculation methods are extremely inaccurate for the regulation of the internal combustion engine, at least in some operating situations.

Disclosure of Invention

The object of the present invention is to at least partially solve the problems set forth in relation to the prior art. In particular, a method should be specified by which the exhaust gas back pressure prevailing in the second section, i.e. downstream of the exhaust gas turbocharger, can be determined as accurately as possible. The exhaust gas back pressure thus obtained can be used for different settings of the internal combustion engine, so that an efficient operation of the internal combustion engine is achieved.

A method according to the invention helps to solve this task. The features which are individually listed in the patent claims can be combined with one another in a technically meaningful manner and can be supplemented by facts from the description of the description and/or details from the drawings, in which further embodiment variants of the invention are indicated.

A method for operating an internal combustion engine having an exhaust gas line is proposed. The exhaust gas line conducts exhaust gas from the internal combustion engine via the exhaust gas turbocharger (for example to the surroundings, if possible at least partially back to the internal combustion engine via the exhaust gas recirculation line). The second pressure in the second section of the exhaust gas line downstream of the exhaust gas turbocharger is determined by measuring a first pressure in the first section of the exhaust gas line downstream of the internal combustion engine and upstream of the exhaust gas turbocharger (for example by means of a pressure sensor, i.e. by means of a first sensor). The determination of the second pressure is derived from the condition or relationship according to which the first pressure corresponds (substantially) to the second pressure in the case of a predetermined crankshaft angle position in a predetermined operating point of the internal combustion engine.

In other words, the method (alternatively or additionally) may be expressed as follows:

1. the first pressure and the second pressure are measured at least during a plurality of operating points of the internal combustion engine and a plurality of crank angle positions of the internal combustion engine,

2. at least one operating point and a crankshaft angle position of the internal combustion engine are identified, wherein the first pressure and the second pressure substantially correspond and the crankshaft angle position or the operating point is identified as a basis for the adjustment.

3. The operation of the internal combustion engine is regulated as a function of the measured first pressure and as a function of the second pressure, which is preset by the regulation base.

Steps 1 and 2 can be carried out (once) during the initialization process (for example on a test stand), while step 3 can be carried out in the motor vehicle during the (driving) operation of the internal combustion engine.

The identification of a "consistent" pressure can be carried out in such a way that a predetermined maximum deviation, which results from a comparison of the first pressure and the second pressure, is not exceeded. The preset maximum deviation may be, for example, 2%, 1% or even 0.5%.

The adjustment basis can be determined in the form of a characteristic line, wherein the identified crankshaft angle position and/or operating point is at least one support or reference variable.

Before step 3, the (pressure) sensor in the second section, if possible, can be removed. It is possible to provide and use a sensor only in the first section for measuring the first pressure.

The second section extends further downstream, in particular from the exhaust gas turbocharger, in particular along a main exhaust gas line (sometimes referred to as the main exhaust system) to the surroundings. In particular, at least one exhaust gas treatment component (particle filter, catalytic converter, flow influencing device, injection device, heating device, etc.) is arranged in the second section.

The second pressure can be obtained in particular between the exhaust gas turbocharger and the exhaust gas treatment component arranged closest downstream of the exhaust gas turbocharger.

The first pressure in the first section depends in particular on the respectively present operating point and on the change in the crankshaft angular position (in the respective operating point). Depending on the crankshaft angular position, an exhaust valve of the combustion chamber is actuated, so that exhaust gases can escape from the combustion chamber into the first section. It is then ascertained that the first pressure upstream of the exhaust gas turbocharger has the same value as the second pressure downstream of the exhaust gas turbocharger in the operating point to be specified and for the specified crankshaft angular position which then exists in the specified manner. It is also ensured that this point in time can be determined very precisely in the first course of the first pressure, so that the second pressure can be derived from the first course of the first pressure with high accuracy.

It is also known that the second pressure has a defined second course as a function of the course of the measured first pressure.

In particular, it is derived from these conditions that the second course of the second pressure can be determined as a function of the measured first course of the first pressure. In addition, the change in the second pressure, and thus the exhaust gas back pressure prevailing in the second section of the exhaust gas line, is determined as a result of the measured first pressure, in particular in the determined operating point and in the case of a determined crankshaft angular position.

The exhaust gas back pressure determined in this way (accurately) can be used, for example, for regulating an internal combustion engine. In addition, a change in the exhaust gas back pressure can be determined via a change in the measured first pressure and thus the acquired second pressure. The change in the exhaust gas backpressure is caused in particular by increased loading of the exhaust gas treatment component, for example arranged in the second section, with soot. By ascertaining a change in the exhaust gas backpressure, the state of the exhaust gas treatment component (i.e. for example the pressure loss at the exhaust gas treatment component) can be determined, among other things. Preferably, a time for regeneration of the exhaust treatment component may be determined. In addition, the efficiency of the regeneration can also be checked via the exhaust gas backpressure present.

In particular, it is proposed to operate the internal combustion engine in a test bench method in order to obtain the operating point and the crankshaft angle position.

In the test stand method, a second (pressure) sensor can be arranged in the second section, and in this way the second pressure and the second profile in the second section are detected in a measurement-technical manner. In the test stand method, therefore, an operating point and a crankshaft angle position can be determined for each configuration of the internal combustion engine, the exhaust gas line, the exhaust gas treatment component, the drive train (for example the transmission, an additional drive unit, etc.), in which the values of the first pressure and the second pressure are of the same magnitude.

The operating point and the crankshaft angle position thus obtained in the test stand method can then be used in particular in the method already described, so that an internal combustion engine of the same type (in the same configuration as used in the test stand method) which is produced in large numbers can be used without the second sensor.

The operating point of the internal combustion engine depends in particular on the currently existing operating parameters of the internal combustion engine (ignition time, injection quantity, compression ratio, etc.), the exhaust gas mass flow, the position of the actuator of the turbocharger and the position of the camshaft.

In particular, for the test bench method, the state of the exhaust gas line downstream of the exhaust gas turbocharger in the second section with respect to the flow resistance and the resulting current exhaust gas back pressure is known (or is detected in the context of the test bench method). The test stand method includes at least the steps of:

a) Measuring a first pressure profile with a first sensor during operation of the internal combustion engine;

b) Measuring a profile of the second pressure with the second sensor during operation of the internal combustion engine;

c) An operating point and a crankshaft angular position are obtained in which the first pressure (substantially) corresponds to the second pressure.

The state of the exhaust gas line comprises, for example, the loading of the at least one exhaust gas treatment component in the second section. The state includes in particular knowledge about all factors influencing the exhaust gas back pressure in the second section. In particular, this is (only) a factor which does not change, for example, in the case of a gas feed (without soot and without reaction in one of the exhaust-gas treatment components or with the second section of the exhaust-gas line).

In particular, from the knowledge that the first pressure or the first profile changes from this known state, one or more causes for the change derived therefrom of the second pressure or the second profile can be inferred. The loading state of the exhaust gas treatment component (e.g., a particle filter) can thus be detected in particular.

Starting from step c), a characteristic curve for an adaptation value (apdationsert) can preferably be determined, by means of which the second pressure is determined from the measurement of the first pressure for further operating points of the internal combustion engine. The characteristic line includes in particular the operating point and the crankshaft angle position obtained in step c) as support points and is thus generated for the other operating points. In particular, it is possible via the adaptation value to determine the second pressure also starting from the measured first pressure in these other operating points.

The second pressure in the second section and thus the actual exhaust gas back pressure are determined in particular during operation of the internal combustion engine as a function of the change in the first pressure.

The current exhaust gas back pressure can be used at least for the following regulation methods:

(1) Adjusting a charging pressure for the internal combustion engine (in particular a pressure provided on a fresh air side of the internal combustion engine);

(2) Regulating the ventilation mode of the internal combustion engine (in particular, the fresh air, exhaust gases, fuel are supplied thereby for combustion in the combustion chamber of the internal combustion engine and the exhaust gases are discharged from the combustion chamber; in addition, the ignition time, the valve opening time, etc.);

(3) Correcting the ventilation mode according to the current exhaust back pressure;

(4) Diagnosing exhaust gas turbocharger components (e.g. to analyze exhaust gas turbocharger speed in order to avoid exceeding a predetermined limit speed; to protect the exhaust gas turbocharger from mechanical and/or thermal damage);

(5) The regeneration of the exhaust gas treatment component arranged in the second section (for example a particle filter in which, for example, the temperature of the exhaust gas is increased or provided at least temporarily) is regulated.

These adjustments are dependent in particular on the exhaust gas back pressure prevailing in the second section of the exhaust gas line downstream of the exhaust gas turbocharger.

In particular, at least one exhaust gas treatment component (e.g., a particle filter) is arranged in the second section, by means of which the exhaust gas backpressure prevailing in the second section upstream of the exhaust gas treatment component is influenced at least as a function of the loading of the exhaust gas treatment component with soot. In particular, the loading can be determined by determining the current exhaust gas back pressure (e.g. the second pressure). In particular, the effect of the performed regeneration of the particulate filter can thus also be checked.

For example, the loading of the particle filter represents, in particular, the amount or mass of solids (such as, for example, soot particles) currently stored in the particle filter. Particulate filters in the present sense are in particular so-called wall-flow filters, i.e. components with a plurality of channels (for example of the type according to a honeycomb structure), which are in particular closed to one another and therefore require the exhaust gas with solids to pass through gas-permeable or porous walls. Here, solids are deposited and/or trapped at or in the wall. As loading increases, the walls or channels become clogged.

Furthermore, a computer program is proposed, which is set up to carry out the method already described. In particular, an engine control system is proposed, which at least partially implements the method proposed herein.

Furthermore, a machine-readable storage medium (for example in a control unit associated with an internal combustion engine) is proposed, on which the computer program that has been described is stored.

In addition, an internal combustion engine is proposed, which has an exhaust gas line, by means of which exhaust gases can be conducted from the internal combustion engine via an exhaust gas turbocharger. The internal combustion engine is provided in particular for being built into or arranged in a motor vehicle.

The exhaust gas line has a first section downstream of the internal combustion engine and upstream of the exhaust gas turbocharger and a second section downstream of the exhaust gas turbocharger. A first sensor is arranged in the first section for measuring a first pressure. The internal combustion engine further comprises a controller which is suitable for carrying out the method or the implementation already described and which is designed to be suitable for carrying out the method or the implementation already described or to implement the method.

The method is particularly useful for all types of internal combustion engines (gasoline engines, diesel engines, etc.) and is particularly usable in conjunction with further drive units (electric drives).

Embodiments of the proposed method are applicable to the proposed internal combustion engine, computer program and storage medium and vice versa.

It is to be understood that the terms "first", "second" … "are used here primarily (exclusively) to distinguish a plurality of objects, variables or processes of the same type, i.e. in particular without imposing a predetermined dependency and/or sequence of these objects, variables or processes on one another. If dependency and/or order is necessary, this is explicitly stated herein or will be apparent to one of ordinary skill in the art in the context of learning the specifically described design.

Drawings

The invention and the technical field are explained in more detail later on with reference to the figures. It should be noted that the present invention should not be limited by the illustrated embodiments. In particular, it is also feasible to refine and combine some aspects of the facts explained in the figures with other components and knowledge from the description and/or the figures, as long as they are not explicitly presented otherwise. It should be noted in particular that the figures and the especially presented size ratios are only schematic. The same reference symbols denote the same objects, so that explanations from other figures may be considered as supplementary if possible. Wherein:

FIG. 1 shows an internal combustion engine with an exhaust gas line; and is

Fig. 2 shows a pressure time line diagram.

REFERENCE SIGNS LIST

1. Internal combustion engine

2. Exhaust gas line

3. Exhaust gas

4. Exhaust gas turbocharger

5. First pressure

6. The first section

7. Second pressure

8. Second section

9. Operating point

10. Angular position of crankshaft

11. Exhaust gas backpressure

12. First direction of movement

13. First sensor

14. The second direction

15. Second sensor

16. Characteristic line

17. Exhaust gas treatment component

18. Loading

19. Computer program

20. Machine-readable storage medium

21. Controller

22. Time.

Detailed Description

Fig. 1 shows an internal combustion engine 1 with an exhaust gas line 2. Exhaust gas 3 is conducted from the internal combustion engine 1 via an exhaust gas turbocharger 4 via an exhaust gas line 2. The exhaust gas line 2 has a first section 6 downstream of the internal combustion engine 1 and upstream of the exhaust gas turbocharger 4 and a second section 8 downstream of the exhaust gas turbocharger 4. In the first section 6, a first sensor 13 is arranged for measuring the first pressure 5. The internal combustion engine 1 additionally comprises a controller 21 which is adapted to carrying out the described method.

Via the measurement of the first pressure 5 in the first section 6 of the exhaust line 1, a second pressure 7 in a second section 8 of the exhaust line 2 downstream of the exhaust turbocharger 4 is determined. The determination of the second pressure 7 is derived from the condition that the first pressure 5 corresponds to the second pressure 7 in the case of a determined crankshaft angle position 10 in a determined operating point 9 of the internal combustion engine 1.

In the second section 8, exhaust gas treatment components 17 (particle filters, catalytic converters, flow influencing devices, injection devices, heating devices, etc.) are arranged.

In the test stand method, a second (pressure) sensor 15 (indicated here by dashed lines) can be arranged in the second section 8 and thus detect the second pressure 7 and the second profile 14 in the second section 8 in a measurement-technical manner. In the test stand method, therefore, for each configuration of the internal combustion engine 1, the exhaust gas line 2, the exhaust gas treatment component 17, the drive train (e.g. transmission, additional drive unit, etc.), the operating point 9 and the crankshaft angle position 10 can be determined, in which the values of the first pressure 5 and the second pressure 7 are of the same magnitude.

The operating point 9 and the crankshaft angle position 10 thus obtained in the test stand method can then be used in the method already described, so that an internal combustion engine 1 of the same type (as the configuration used in the test stand method) manufactured in large numbers can be used without the second sensor 15.

In the second section 8, an exhaust gas treatment component 4 (for example, a particle filter) is arranged, by means of which the exhaust gas backpressure 11 prevailing in the second section 8 upstream of the exhaust gas treatment component 4 is influenced at least as a function of the loading 18 of the exhaust gas treatment component 17 with soot. The loading 18 can be determined by the current exhaust gas back pressure 11 (or second pressure 7) determination.

Controller 21 may detect pressure 5,7. A computer program 19 is stored in a controller 21, which is stored in a machine-readable storage medium 20. Further, the controller 21 stores a characteristic line 16.

Fig. 2 shows a pressure time line diagram. The pressure 5,7 is plotted on the vertical axis. Time 22 or repeated crankshaft angle positions 10 on the horizontal axis.

The first pressure 5 in the first section 6 changes as a function of the respectively present operating point 9 and as a function of the crankshaft angular position 10 (in the respective operating point 9). Depending on the crankshaft angular position 10, the exhaust valve of the combustion chamber is actuated so that exhaust gas 3 can escape from the combustion chamber into the first section 6. It is now ascertained that the first pressure 5 upstream of the exhaust-gas turbocharger 4 in the specific operating point 9 and for the specific crankshaft angle position 10 which then exists has the same value as the second pressure 7 downstream of the exhaust-gas turbocharger 4 (see the intersection of the first course 12 of the first pressure 5 and the second course 14 of the second pressure 7). It is also ensured that this point in time can be determined very precisely in the first course 12 of the first pressure 5, so that the second pressure 7 can be derived with high accuracy from the first course 12 of the first pressure 5.

It is also known that the second pressure 7 has a second profile 14 which is dependent on the first profile 12 of the first pressure 5.

From these conditions, it is derived that the second profile 14 of the second pressure 7 can be determined as a function of the first profile 12 of the first pressure 5. In addition, since the first pressure 5 changes in particular in a specific operating point 9 and in the case of a specific crankshaft angular position 10, a change in the second pressure 7 and thus the currently existing exhaust gas back pressure 11 in the second section 8 of the exhaust gas line 2 can be determined.

Claims

1. A method for operating an internal combustion engine (1) having an exhaust gas line (2) which conducts exhaust gas (3) from the internal combustion engine (1) via an exhaust gas turbocharger (4), wherein a second pressure (7) in a second section (8) of the exhaust gas line (2) downstream of the exhaust gas turbocharger (4) is determined by measuring a first pressure (5) in a first section (6) of the exhaust gas line (2) downstream of the internal combustion engine (1) and upstream of the exhaust gas turbocharger (4); wherein the determination of the second pressure (7) is derived from the relationship according to which the first pressure (5) corresponds to the second pressure (7) in the case of a predetermined crankshaft angle position (10) in a predetermined operating point (9) of the internal combustion engine (1), wherein the internal combustion engine (1) is operated in a test bench method in order to determine the operating point (9) and the crankshaft angle position (10), and wherein the state of the exhaust gas line (2) downstream of the exhaust gas turbocharger (4) with respect to the flow resistance in the second section (8) and the resulting current exhaust gas back pressure (11) is known for the test bench method; wherein the test stand method comprises at least the steps of: a) Measuring a first course (12) of the first pressure (5) with a first sensor (13) during operation of the internal combustion engine (1); b) Measuring a second profile (14) of the second pressure (7) with a second sensor (15) during operation of the internal combustion engine (1); c) -acquiring said operating point (9) and said crankshaft angular position (10), in which said first pressure (5) corresponds to said second pressure (7).

2. Method according to claim 1, wherein starting from step c), a characteristic curve (16) for an adaptation value is obtained, by means of which the second pressure (7) is determined from the measurement of the first pressure (5) for the further operating point (9) of the internal combustion engine (1).

3. A method according to claim 1 or 2, wherein the second pressure (7) and thus the prevailing exhaust gas back pressure (11) in the second section (8) are determined during operation of the internal combustion engine (1) as a function of a change in the first pressure (5).

4. A method according to claim 3, wherein the current exhaust gas back pressure (11) is used at least for the following regulation methods:

(1) -regulating a charging pressure for the internal combustion engine (1);

(2) -adjusting the breathing mode of the internal combustion engine (1);

(3) Diagnosing exhaust turbocharger overspeed;

(4) Regulating the regeneration of an exhaust gas treatment component (17) arranged in the second section (8).

5. A method according to claim 3, wherein at least one exhaust gas treatment component (17) is arranged in the second section (8), by means of which the current exhaust gas back pressure (11) in the second section (8) upstream of the exhaust gas treatment component (17) is influenced at least in dependence on the loading (18) of the exhaust gas treatment component (17) with soot; wherein the load (18) can be determined by determining the current exhaust gas back pressure (11).

6. An apparatus for an internal combustion engine comprising a controller and a memory having stored thereon instructions that, when executed, implement the method of any one of claims 1 to 4.

7. A machine-readable storage medium (20) having stored thereon instructions which, when executed, carry out the method according to any one of claims 1 to 4.

8. An internal combustion engine (1) having an exhaust gas line (2) by means of which exhaust gases (3) can be conducted from the internal combustion engine (1) via an exhaust gas turbocharger (4), wherein the exhaust gas line (2) has a first section (6) downstream of the internal combustion engine (1) and upstream of the exhaust gas turbocharger (4) and a second section (8) downstream of the exhaust gas turbocharger (4); wherein a first sensor (13) is arranged in the first section (6) for measuring a first pressure (5); wherein the internal combustion engine (1) additionally comprises a controller (21) adapted to perform the method according to any of the preceding claims 1 to 4.